Stripping Concrete Before Resealing Yields the Best Results

One of the easiest ways to strip off old sealer from an existing patio is to use a fabric blanket coated with liquid stripper. Photos courtesy of Nox-Crete.

Anything worth doing is worth doing right. Don’t cut corners and expect quality results. These may sound like clichés designed to get folks to toe the line but more often than not, I’ve found them to be absolutely true. In the same way that you get what you pay for, you get out of something what you put into it.

For example, suppose a backyard concrete patio is ready for a facelift. The acrylic sealer applied years ago is worn out and the surface is blistered, chalky and cloudy. The impression it will leave on guests is not the impression wanted. So what’s the remedy? Technically, you could just reapply a sealer and hope for the best. But if you want to do it right, you start by prepping the surface for a new sealer by stripping away the old sealer. The results you see on the surface are only as good as the foundation.

Off with the old
There are several common approaches to removing acrylic sealer and none of them are easy. Each of these options will work — eventually — but there are pros and cons to weigh.

First, roll out the fabric blanket.

After the blanket is in place, apply the liquid stripper.

When the blanket is dry and impregnated with old acrylic sealer, peel it up.

Pressure wash the patio to remove the remaining chemically softened old acrylic sealer.

Hazardous solvents. A solvent like xylene is effective at removing acrylic. It dissolves (“softens”) the acrylic and allows for removal. However, solvents such as xylene have a harsh smell, are flammable, dangerous for your skin, and shouldn’t be used around children, pets and plants. Most importantly, these types of solvents are not EPA compliant for use in this way.

Stripper + pressure washers. A compliant floor coating stripper combined with a power washer can blast away old acrylic pretty effectively. This method works but typically requires significant “elbow grease” to soften the acrylic. The step of removing the softened acrylic by pressure washing requires significant prep work to protect landscaping, siding and other surfaces from splatter of the softened acrylic and over-spray of the stripper that could strip other surfaces. Pressure washing without the benefit of a stripper is generally not very effective.

Sandblasting or grinding. Aggressive techniques such as these may get the job done but it will often compromise the original surface and aesthetics of the concrete. It also is laborious, creates a mess and requires significant cleanup.

So, what’s the best option for removing worn-out acrylic sealer, particularly in a confined space like a backyard patio? Biodegradable blanket stripper treatments are a great option in this type of situation.

Blanket benefits
This stripper method is easy to use, safe and highly effective. Sweep the surface clean and remove all debris. Cover your affected surfaces with a specialized biodegradable cellulose blanket and apply a biodegradable stripper right over the top. Use a brush for edges and small spaces, and a 3/8-inch nap paint roller for the larger surface areas. Spread the solvent on evenly until the blanket is saturated. Let the blanket dry completely, then simply pull it up and throw it away.

Tips for optimal results:

Make sure the surface is dry for 24-48 hours before using a blanket stripper.

Don’t forget the valleys, joints and ridges. Keep rolling until the whole blanket becomes translucent and the concrete is visible through the fabric.

Dry time of the biodegradable solvents is variable depending on weather conditions, but typical dry time is between two and six hours.

Allow at least 24 hours after stripping before applying a coating or sealer.

Not only is this method easy, fast and effective, it’s also environmentally friendly when you choose biodegradable materials. The stripped chemicals are absorbed into the blanket instead of the nearby soil. The blanket system may not remove multiple sealer coats in one application and may require additional applications for complete removal.

On with the new
You’ve successfully removed the faded, delaminated sealer from your surface and you’re ready to reseal. Acrylic sealers are easy to apply and economical. They create a thin protective film that gives concrete a wet look. Acrylic sealers are available in solvent- and water-based formulas.

Craig Coppersmith, vice president of technical sales and marketing at Nox-Crete Products Group in Omaha, Nebraska, is a licensed professional engineer with more than 25 years of experience in manufactured products for concrete construction. He is an active member of ACI and ASCC, and has presented at World of Concrete. Craig can be reached at [email protected]

Southwestern Paint and Supply’s Hydro Guard, a sealer designed 22 years ago for secondary containment of chemicals and for sealing exterior stucco, has been discovered in recent years by decorative concrete fabricators who appreciate its thinness and praise its stain resistance and durability.